What is the recommended dosage and use of GABApentin (Gabapentin) for managing seizures and neuropathic pain?

Gabapentin Dosing and Use

For neuropathic pain, start gabapentin at 300 mg on day 1, increase to 600 mg/day on day 2, then 900 mg/day on day 3, and titrate to a target dose of 1800 mg/day divided three times daily, with a maximum of 3600 mg/day if needed. 1

Neuropathic Pain Management

Initial Dosing Strategy

• Begin with 300 mg as a single dose on day 1, advance to 300 mg twice daily on day 2, then 300 mg three times daily (900 mg/day total) on day 3 1
• The American Academy of Neurology supports starting at 100-300 mg at bedtime or 100-300 mg three times daily, with increases by 100-300 mg every 1-7 days as tolerated 2, 3
• Slower titration (dose increments of 50-100% every few days) is recommended for elderly patients or those who are medically frail 2

Target and Maximum Doses

• The effective dose range is typically 1800-3600 mg/day in three divided doses 3, 1, 4
• In clinical trials, 1800 mg/day demonstrated efficacy, though doses up to 3600 mg/day were well tolerated and may provide additional benefit in some patients 1, 4
• The maximum single dose is 1200 mg as part of the 3600 mg/day maximum, with no more than 12 hours between doses 1
• An adequate trial requires 2 months or more to determine full efficacy 3

Evidence for Specific Conditions

• Postherpetic neuralgia: 32% of patients achieve substantial benefit (≥50% pain relief) at doses ≥1200 mg/day versus 17% with placebo (NNT 6.7), and 46% achieve moderate benefit (≥30% pain relief) versus 25% with placebo (NNT 4.8) 5
• Painful diabetic neuropathy: 38% achieve substantial benefit at doses ≥1200 mg/day versus 21% with placebo (NNT 5.9), and 52% achieve moderate benefit versus 37% with placebo (NNT 6.6) 5

Epilepsy with Partial Onset Seizures

Adults and Adolescents ≥12 Years

• Start at 300 mg three times daily 1
• Maintenance dose is 300-600 mg three times daily 1
• Doses up to 2400 mg/day are well tolerated in long-term studies, and 3600 mg/day has been administered to some patients for shorter durations 1
• Maximum interval between doses should not exceed 12 hours 1

Pediatric Patients (Ages 3-11 Years)

• Starting dose range: 10-15 mg/kg/day in three divided doses 1
• Ages 3-4 years: Maintenance dose of 40 mg/kg/day in three divided doses 1
• Ages 5-11 years: Maintenance dose of 25-35 mg/kg/day in three divided doses 1
• Titrate upward over approximately 3 days to reach maintenance dose 1
• Doses up to 50 mg/kg/day have been well tolerated in long-term studies 1

Special Populations

Renal Impairment

• CrCl ≥60 mL/min: 900-3600 mg/day in three divided doses 1
• CrCl 30-59 mL/min: 400-1400 mg/day in two divided doses 1
• CrCl 15-29 mL/min: 200-700 mg/day as single daily dose 1
• CrCl <15 mL/min: 100-300 mg/day as single daily dose 1
• Hemodialysis patients: Maintenance doses based on creatinine clearance plus supplemental post-hemodialysis dose (125-350 mg) after each 4-hour dialysis session 1

Elderly Patients

• Lower starting doses and slower titration are recommended due to increased risk of decreased renal function and heightened sensitivity to side effects 2, 6, 3
• Dose selection should be based on creatinine clearance values 1

Administration and Discontinuation

Administration

• Take with or without food 1
• If dividing scored 600 mg or 800 mg tablets, use the unused half-tablet as the next dose within 28 days 1
• Gabapentin has nonlinear pharmacokinetics due to saturable absorption, making dosing less predictable than pregabalin 2

Discontinuation

• Never abruptly discontinue gabapentin 2
• Taper gradually over a minimum of 1 week (longer periods may be needed at prescriber's discretion) to avoid withdrawal symptoms 2, 1

Adverse Effects

Common Side Effects

• Dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (14%) occur with gabapentin 5
• Most adverse effects are dose-dependent, mild to moderate, and typically subside within approximately 10 days from initiation 4, 7
• 63% of patients experience at least one adverse event versus 49% with placebo (NNH 7.5) 5

Serious Adverse Events

• Adverse event withdrawals occur in 11% with gabapentin versus 8.2% with placebo (NNH 30) 5
• Serious adverse events are no more common with gabapentin (3.2%) than placebo (2.8%) 5

Minimizing Side Effects

• Start with lower dosages and titrate cautiously 2, 3
• Consider divided dosing to minimize peak-related side effects 6
• Monitor for dizziness, somnolence, and neurological side effects, especially during dose titration, with particular caution in elderly patients at risk for falls 6

Clinical Pitfalls

• Inadequate dosing: Many patients in clinical practice receive only 1800 mg/day when higher doses (up to 3600 mg/day) may be needed for optimal pain control 3, 4
• Insufficient trial duration: Allow at least 2 months to assess full efficacy before concluding treatment failure 3
• Abrupt discontinuation: Always taper to avoid withdrawal symptoms 2, 1
• Ignoring renal function: Failure to adjust doses in renal impairment can lead to toxicity 1